1. Field of the Invention
The present invention relates to a method of making capsules of dehydrated sludge and an apparatus therefor.
2. Description of the Related Art
Processing used batteries, EAF dust or incineration ash requires processing sludge or by-product which often requires the step of agglomeration of sludge. In the conventional method, sludge agglomeration is generally started with moisture adjustment by dehydration of the sludge or addition of water to the sludge. After the water content of the sludge is adjusted (to adjust the water content, complete drying of the sludge is often necessary), a binder is added to the sludge. The mixture is kneaded and is then formed by an agglomeration machine (such as a briquetting machine, a pelletizer or a sintering machine). Generally, this sludge agglomeration is repeated more than once to produce sludge agglomerate having a suitable size. That is, it requires facilities for classifying the agglomerate having a suitable size, grinding the agglomerate which is larger than the upper limit size together with those which are smaller than the lower limit size, and returning the said ground materials to the sludge feed.
The agglomerate of sludge made in the manner described above must be strong enough to withstand subsequent steps, such as conveying, drying, sintering, melting or chemical reaction. Therefore, they are subjected to various troublesome tests, such as crushing strength test, wearing test, shattering test, drying and sintering reaction test, in order to optimize the said steps. Not only is the sludge agglomeration process complicated as mentioned above, but also quality control conducted in continuous or batch operation for the said process is not an easy one.
The sludge agglomerate made through even such a complicated process may be cracked, worn or ground unavoidably in the subsequent processes. The equipment for making sludge agglomerate is expensive due to the above-described complicated process, and requires large space for installation. When the equipment is incorporated in a relatively small scale plant for processing used dry batteries, EAF dust or incineration ash, it occupies a large space as compared with the main equipment and thereby it is quite unreasonable.